i HINTS ON DRAWING 15 



might in all cases colour the alimentary canal yellow, the 

 arteries red, the veins blue, glands brown, cartilage green, 

 and so on. 



Make your drawings on one side of the page only ; the 

 opposite side can then be used for explanations of the 

 figures. 



Never insert on your original sketches anything you have 

 not actually seen ; you can copy as many other figures as you 

 like from various sources, but these should be kept apart 

 from your own original drawings. 



Directions for the examination of the external characters 

 of the adult frog, as described in this chapter, are given at 

 the end of Chapter II., p. 31 ; and of the eggs and tadpoles 

 in Chapter XII., p. 212. 



